The present invention relates to a device for regulating the flow of a fluid.
In general terms the problem which is to be solved by the present device is to bring about a given pressure drop for a given nominal flow rate and a given downstream pressure, without producing cavitation.
This device is more particularly intended for use in the regulation of the flow of a cooling fluid circulating in the base of a liquid metal-cooled nuclear reactor assembly. It is known that the core of a nuclear reactor cooled by a liquid metal, generally formed by sodium comprises the juxtapositioning of vertically arranged assemblies, constituted in each case by an elongated case open at its upper end and provided at its lower end with a positioning support. These assemblies are conventionally supported by a rigid supporting member supplied by means of circulating pumps with liquid sodium from the heat exchangers.
In order to bring about an appropriate mechanical fixing of the assembly positioning support, it is fitted on to or into a carrying member integrated into the core supporting member. This carrying member also supplies the liquid sodium to the base of the assembly.
The flow rates of the cooling liquid sodium in these assemblies must be appropriately adjusted as a function of their position. Various devices installed in the carrying members or assembly bases are known, which make it possible to regulate the cooling fluid flow.
Thus, in the hitherto known fast neutron nuclear reactors, devices are conventionally used which consist of a stack of diaphragms having a central hole, annular orifices or multiple perforations, of the type described in French Pat. No. 7520819 of July 2, 1975 and French Pat. No. 7835201 of Dec. 14, 1978. These simply constructed devices lead to significant overall dimensions, whilst only giving reduced performance levels in connection with the cavitation.
Another device is described in French Pat. No. 2 065 744 filed on Oct. 21, 1970 and entitled "Device for regulating the flow of a liquid". This device has a series of thin barriers spaced in the flow direction, each barrier being constituted by a metal sheet cooperating with regulatable devices forming a mask and which are able to modify the effective surface presented to the liquid flow.
However, for high hydraulic energy dissipation levels, the mechanical strength of the metal sheets is not completely adequate. Moreover, such a design does not lead to an optimum radial compactness.